In a packaging line for containers of any product, said containers pass through various treatment-stations. Thus, in the particular case of a bottling unit, it is common to have the containers, especially if they are in the form of bottles, pass through a washing unit, under a bottler, then to a labeller and optionally to a packager.
Between these different treatment stations, these containers are moved by transporters designed to adapt themselves to the respective production rhythms of said stations. To do this, it is necessary to form buffer inventories of containers at the level of these intermediate transporters. Moreover, these buffer inventories often make it possible to avoid completely stopping a facility, for example a bottling line, when a station downstream is temporarily stopped for any intervention.
To form such buffer inventories, it is more especially intended that accumulation tables be inserted at the level of the intermediate transporters, tables with a stockpiling capacity that determines, among others, the time available to an operator for intervening in a station downstream without requiring a complete shutdown of the production line. This results in that flexibility of use of the packaging facility is dependent on the container accumulation capacity between two successive treatment units, a large accumulation capacity resulting in high flexibility of use.
Document WO00/41155 describes an accumulation table of this type that is composed of a juxtaposition of transport lines, of which certain ones define a so-called feed conveyor and others that advance more slowly, forming accumulation
According to this document, the containers are supplied to the accumulation table at its upstream end via a feed transporter that is directly lengthened by a feed conveyor. When the containers arrive in the downstream part of the table and cannot continue to advance normally, they are automatically pushed back, under the influence of the following containers, toward the accumulation conveyor or conveyors extending from one side or the other of the feed conveyor. This results in an accumulation of containers for forming a buffer inventory.
It should be noted that in the accumulation period per se, the accumulation conveyor or conveyors are stopped. Conversely, when the flow is running normally on the discharge transporter at the downstream end of the table, the accumulation conveyors are moving and advance more slowly than the feed conveyors, as already indicated above.
The speed difference between the feed conveyor or conveyors and the accumulation conveyor or conveyors involves the formation of preferred flows along the table.
It has been found that these preferred flows that are formed more or less systematically in the extension of a feed conveyor are the result of incorrect distribution of the containers on the table, more especially in the accumulation phase. Thus, a container that is located on a feed conveyor and that is in contact with other containers, especially containers distributed on the accumulation conveyors, is exposed, under the influence of the advance of the feed conveyor, to a thrust with an axial component, i.e., in the normal direction of advance of these containers, that is essentially greater than the component that is transverse to the table and thus in the direction of advance.
This results in that these containers that are located on a feed conveyor, following a lateral direction, very easily push back the containers that are located on the accumulation conveyors and, due to the fact that they are advancing more quickly, they prevent integration of these containers located on the feed conveyors into the preferred flux that has been formed in this way.
It has been suggested that these disadvantages be remedied by routing the containers stockpiled on the accumulation table according to a perfect or more or less perfect arrangement of staggered rows, i.e., such that these containers are distributed in rows extending crosswise to the table and consequently advancing abreast. Moreover, the containers that are in contact with one another in a row are arranged in staggered rows with those of the preceding and following rows.
Thus, a container that is not directly juxtaposed to a lateral guide rail comes into contact with the two containers of the preceding row, but likewise with two other containers of the following row. This is followed by a re-alignment of the containers in one direction of roughly 30° relative to the axis of the table, i.e., relative to the direction of advance of the containers. Such a container is exposed to thrusts following the aforementioned 30° angles relative to the longitudinal axis of the table, such that it has a tendency to be pushed back laterally and thus can no longer insert itself into the preferred axial flow. Since a perfect arrangement in staggered rows prevents the presence of empty space between the containers, the containers located on the accumulation conveyors cannot in their turn be pushed back laterally to promote passage of the containers upstream.
This results in that the containers located on the accumulation conveyor or conveyors are naturally pushed downstream from the table without a preferred path for the containers located on the feed conveyor or conveyors being able to be set up.
To eliminate these disadvantages, it has been proposed that a perfect or more or less perfect distribution of the containers in staggered rows on the accumulation table be ensured, by simply providing on one side and/or the other of the table, on the lateral guide rails, one or more baffles with a defined amplitude. Such a solution is described especially in document U.S. Pat. No. 4,623,059.
Via these baffles of a defined amplitude, the containers undergo a modification of their arrangements relative to one another, without, however, producing a blockage; this specifically results in allowing them to assume a distribution under the aforementioned conditions with elimination of the empty space between these containers.
This results in that the containers advance necessarily simultaneously over the entire width of the accumulation table without there being any differentiation between the containers located on the feed conveyors and those located on the accumulation conveyors.
These baffles in the form of a sawtooth tend to promote a blockage of the containers at the bottom of the teeth, however, which results in the necessary adaptation of these baffles to the diameter of the containers. Moreover, providing such added baffles entails a relatively major expenditure of labor and accessories for fixing and adjusting them in position in order to achieve a correct sequence of detours of the containers individually and in order to route them into the main flow according to the predetermined arrangement in staggered rows. Moreover, the very fact of adding these baffles entails additional risks of problems such as deformations or the like and thus the necessity of additional maintenance interventions.